I can't find link that I originally saw. However, I think this chiller would be a nice size for 125-175 gallons. I don't see why you wouldn't be able to use it on something smaller if you wanted though.

ALSO! I will include a mag drive pump for use with it. I'm not sure the specs but should be able to get them for you if you're interested. I do know that it was the perfect amount of flow through the chiller. About the middle of the road for what Current recommended.